IMHO polygon count is not nearly as important as texture, lighting (and therefore also shadows) and animation quality.
Their polygon count is impressive and the object detail looks awesome, but, as other people commented here, I wonder how well it will hold up when dynamic objects, animation and dynamic lighting are added.
General consensus last time this rolled around, which I see no reason to change, is that once you add "dynamic objects [or] animation", it completely stops working, so... it probably won't hold up at all.
Most obvious comparison comes in right at the 4:00 mark, where you can see the "polygonal" grass waving gently in the wind, then at 4:22 their "unlimited detail" grass appears to be carved out of some sort of grass-colored rock. Also observe how at the end they are excited about their improvement in "the lighting", by which they mean, the lighting that you will get.
Their polygon count is impressive and the object detail looks awesome, but, as other people commented here, I wonder how well it will hold up when dynamic objects, animation and dynamic lighting are added.